Thin Film Transistor-Liquid Crystal Displays (TFT-LCD) have become the mainstream in the market due to many advantages thereof such as high picture quality, high space utilization, low power consumption, no radiation etc. In a TFT-LCD panel, a color film substrate and an array substrate are arranged opposite to each other to form a liquid crystal cell. In order to ensure a uniform thickness of the liquid crystal cell, a photo spacer (PS for short) plays an important role.